1. Field of the Invention
The present invention generally relates to motor vehicle seats and, more specifically, to the forming of a headrest for such seats.
2. Discussion of Prior Art
Different types of headrests for motor vehicle seats are known. Two types of headrests can be mentioned, those integrating an adjustment mechanism and simpler ones for which the position of a body of the headrest with respect to spindles engaged in the backrest of the seat is fixed. In the first category, the spindles generally form the two branches of a U having its base fastened to a frame of the headrest. In the second category, to which the present invention more specifically applies, the spindles are formed of metal rods which are individually connected to the headrest frame. The body or frame of the headrest then more and more often is a plastic frame or case having sleeves into which the spindles are engaged. In all cases, the frame is subsequently covered with upholstery (cushioning and cover).
FIG. 1 very schematically shows a lateral view of a motor vehicle seat 1 of the type to which the present invention applies as an example. This seat comprises a seat bottom piece 12 on which is hinged a backrest 14. The seat bottom piece is fastened to floor P of the vehicle, directly or via a guide rail mechanism 16. Backrest 14 supports a headrest 2 formed of a body 3 and of spindles 4 having their free ends engaged in sleeves provided for this purpose in the high portion of backrest 14.
FIG. 2 is a rear perspective view of a usual headrest 2′ of the type having separate spindles 4′. The upper end of each spindle 4′ is engaged in a sleeve 32′ defined by head 3′ of headrest 2′. The ends of the spindles comprise holes intended to receive locking pins 42′ transversely engaged through sleeves 32′ and cooperating with grooves provided in the spindles. These pins are force-fit to block each spindle with respect to body 3′.
A disadvantage of such an assembly is that it requires for an operator to force fit the two locking pins. Further, for security reasons, it is necessary to verify that the headrest is properly assembled. With this assembly principle, it must be attempted to force the separation of the spindle from the headrest to verify that it is properly fastened. A disadvantage is that in case of an incorrect fastening, the plastic frame is damaged and can no longer be used.
It would be desirable to simplify the assembly of spindles in a headrest of plastic-body type.
It would further be desirable to be able to easily verify that the headrest has been properly assembled.
Document EP-A-0743223 describes a headrest structure for a motor vehicle. The upper ends of the spindles of the headrests intended to be engaged into the housings of a body of the headrest comprise, on the one hand, a vertical rib cooperating with a vertical groove of the housing to guide the spindle while it is being introduced and, on the other hand, a horizontal rib cooperating with a horizontal tooth of the housing to block the translation of the spindle. Two different means are thus necessary on the spindle side and on the housing side, respectively for the guiding and to block the translation.